1. Field of the Invention
This invention relates, in general, to a heat-resisting aluminum alloy which is high in mechanical strength not only at ordinary temperatures but also at high temperatures, and more particularly to the heat-resisting aluminum alloy suitable for the material of automotive engine component parts subjected to ordinary to high temperatures.
2. Description of the Prior Art
It is a recent tendency that improved fuel economy has been eagerly desired particularly in the field of automotive vehicles. As a measure for attaining the improved fuel economy, weight reduction of the automotive vehicles has been made by using light weight component parts made, for example, of aluminum alloy. Thus, aluminum alloy has been extensively used as the material of the automotive vehicle component parts, particularly of engine component parts.
However, it is difficult to employ usual aluminum alloy for the material of the engine component parts which are required to have a high mechanical strength throughout a wide temperature range from normal temperatures to about 250.degree. C.
More specifically, so-called high strength aluminum alloy such as one whose designation number is 7075 has a good strength characteristics at normal temperatures but is sharply lowered in strength in a temperature range from normal temperatures to 200.degree. C. In this regard, such high strength aluminum alloy is not suitable for the material of the component parts of automotive engines. The designation numbers of aluminum alloys mentioned hereinabove and hereinafter are adopted by the Aluminum Association in the United States of America.
Regarding so-called heat-resisting aluminum alloy such as one whose designation number is 2218, it is excellent in strength at high temperatures but is lower in strength at normal temperatures. As a result, such heat-resisting aluminum alloy is also not suitable for the material of automotive engine component parts.